Every business tracks something Finocket doesn't ship a box for — a PO number on invoices, a warranty date on items, a lead source on deals. Custom fields let you add exactly those, so your records hold the information you actually work with instead of forcing it into the notes.
Fifteen field types
Pick the right shape for what you're capturing: text, multi-line text, number, decimal, amount, percent, date, checkbox, dropdown, multi-select, URL, email, phone, auto-number (a running series like INV-0001, assigned for you), and lookup (a reference to a client or an item).
On the records that matter
Define fields for any of seven record types — invoices, invoice lines, expenses, items, payments, clients and deals — from Settings → Custom fields. Each field appears on that record's form for everyone in the workspace.
An item field appears everywhere an item is created or edited: the item screens, and both panels you reach from an invoice line — Edit catalog item and the sheet that adds a new item while you are writing the bill. An invoice line field is different: it is typed per line on the document, for something that changes with each sale — a batch, a location, a HUID. If a detail never changes for a product, it belongs on the item instead, so you enter it once.
On the invoices, clients, items and expenses lists a columns button lets you show your own fields beside each row, so a value you were asked to type can be read back without opening the record. Your choice of columns is yours alone and is remembered.
If you have defined no fields yet, every one of these places correctly shows nothing — there is nothing missing, there is simply nothing to show. Start at Settings → Custom fields.
Make them behave
Mark a field required so a record can't be saved without it, and add a validation pattern (a regex) to enforce a shape — a fixed-length code, a specific format. Two switches control where a field is seen: show on PDF puts it on the invoice document, and show on portal exposes it on the client or vendor portal. Leave both off and it's an internal-only field.
In reports, the API and CSV
A custom field rides a stable api name derived from its label, and that same name is used everywhere: it shows up automatically as a column and a filter in the report builder, comes back on the record in the API, and appears as a column in CSV exports. Define it once and it's available across all three.
Custom fields are an application-layer feature — the field definitions and their values live in your workspace's data. They shape and validate what you enter; they aren't a database-level access control.
Related: Report builder, Developers — API keys & webhooks.